Unloading mechanism for rotary compressors



Aug. 15, 1933. M. RIESNER UNLOADING MECHANISM FOR ROTARY COMPRESSORS 2 Sheets-Sheet 1 Filed March 15, 1951 W W l IVLRIESNEFL.

INVENTOR A TTORNE Y Aug. 15 1933.

M. RIESNER UNLOADING MECHANISM FOR ROTARY COMPRESSORS Filed March 13, 1931 2 Sheets-Sheet 2 I EH Ii I '1 I INVENTOR BY WW Patented .Aug. I5, 1933 UNLOADIN G MECH ANISM FOR ROTARY COMPRESSORS Michael Riesner, Cincinnati, Ohio, assignor to Worthington Pump tion, New York, N. 35.,

Application March 13,

7 Claims.

This invention relates to air or gas compressors, and more particularly to that type of compressor embodying a rotor or rotary piston rotating in a cylinder or casing for compressing the air or gas.

An object of the present invention is to provide means for unloading the compressor when the receiver pressure rises to a predetermined degree and for loading it as the receiver pressure falls, such means being automatically controlled by receiver pressure or adapted for manual operation.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing an unloading mechanism for rotary compressors of the preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claims;

In the drawings:

Fig. 1 is a vertical section through a rotary compressor of approved form showing the preferred form of unloading device associated therewith.

Fig. 2 is a detailed section through the dividing wedge or abutment employed in the compressor structure, and

Fig. 3 is a vertical section through a rotary compressor of approved type showing a modified form of unloader mechanism associated therewith.

Referring more particularly to the drawings, the compressor 1 comprises the cylinder 2 in which the rotor 3 rotates for compressing the air or gas. The air or gas to be compressed is drawn into the cylinder 2 through the suction port 4 and the suction inlet 5 and is compressed, being discharged through the discharge port 6 which has a discharge valve 7 of any approved type therein. As is usual,-in compressors of this type a movable abutment 7 is provided which divides the interior of the cylinder 2 about the perimeter of the rotor and separates the suction port 4 from the discharge port 6. In normal operation of rotary compressors the abutment 7 is held in tight engagement with the perimeter of the rotor by various means. However, in the present invention the improved mechanism for unloading and loading the compressor is associated with the movable abutment '7.

The movable abutment 7 is composed of two wedge shaped members 8 and 9, the inclined sides of which engage, as clearly shown in Fig. 2 of the drawings, and these members slide in a suitable guide 10 formed in the housing 11 of the compressor.

The unloading mechanism comprises a cylin and Machinery Corporaa Corporation of Virginia i931. Serial No. 522,278

der 20 which is attached to the housing 11 of the compressor by a connecting sleeve 21. The sleeve 21 is bored to correspond to the bore in which the abutment 7 moves. A piston 22 is mounted in the cylider 20 for reciprocation therein and is connected to the abutment 7 by means of a rod 23. The rod 23 extends slidably through the wedge members 8 and 9 and has a head 24 on its inner end which engages in a recess 25 formed in the wedge member 8, so that when the piston 22 moves inwardly the abutment 7 is free to operate in its normal manner and be yieldably urged into engagement with the perimeter of the rotor 3 by means of the spring 12. The cylinder 20 has a connection-through a pipe 26 with the suction 5, of the compressor 1, so that air or gas under suction pressure will be delivered into the cylinder 20 behind or outwardly of the piston 22 and cooperate with the spring 12 to urge the piston inwardly and position the abutment 7 for normal operation. 7

The inner end of the cylinder 20 inwardly of the piston 22' has a pipe 28 connected thereto which in turn .is connected to a trigger valve 29. The trigger valve 29 may be of any approved construction of trigger valves now used in controlling the unloading of compressors. The trigger valve 29 is connected by a suitable pipe 30 with the receiver (not shown), so that when the pressure in the receiver reaches or goes above a predetermined degree the trigger valve 29 will be operated to admit the air or gas under receiver pressure into the cylinder 20 inwardly of the piston 22 and move the piston 22 outwardly. The moving of the piston 22 outwardly will also move the abutment 7 outwardly away from the perimeter of the rotor 3 and open the discharge port 6 to thesuction port 4 and permit the compressor to idle or to operate in an unloaded noncompressing condition. Should the pressure in the receiver fall below the predetermined degree for which the trigger valve 29 is set then the trigger valve will operate to cut off the passage of pressure fluid under receiver pressure into the cylinder 20 and permit the bleeding of such pressure fluid from the cylinder. When this takes place the suction pressure entering the cylinder 20 outwardly of the piston 22 in cooperation with the spring 12 will move the piston 22 inwardly and relieve the abutment 7, permitting it to operate in its normal manner and consequently allowing the compressor to operate in a loaded condition for compressing air or gas.

In Fig. 3 a modified form of the unloading mechanism is illustrated, which cooperates with the abutment 7' of the compressor structure 1' for controlling the loaded and unloaded operation of the compressor.

In the modified form of unloading mechanism a cylinder 40 is provided in which a pilot piston 41 is mounted and this pilot piston may be operated or moved in any suitable manner, such as, manually or by suitable mechanism (not shown) controlled by receiver pressure, its manner of operation forming no part of the present invention, since there are many practical mechanisms now on the market to perform this function. The cylinder 40 has a port 42 opening thereinto which communicates with the discharge passage 6' of the compressor 1 and when the compressor is operated in a loaded or fluid compressing condi- -tion the pilot piston.41 is positioned, as shown in Fig. 3 of the drawings, with its spaced piston heads 42 and 44 positioned'to permit fluid under discharge pressure or the compressor to flow through the port 42 into the cylinder 40 through the port 45 and into the chamber 46 behind the abutment 7' for holding the abutment in engagement with the perimeter of the rotor 3. When it is desired to unload the compressor the pilot piston 41 is shifted so as to cut oil communication between the ports 42 and 45 and open communication between the ports 45 and the port 47. This latter port 47 establishes com munication between the cylinder 40 and the suction 5' of the compressor and allows the fluid under discharged pressure to bleed from the chamber 46 back into the suction 5 of the compressor and relieve the abutment '7' of the force which holds it in engagement with the perimeter of the rotor 3, thereby allowing the abutment to be easily moved or displaced by the pressure built up in the cylinder 2' by the rotor 3 and consequently permit bypassing between the discharge 6' and suction 5 of the compressor to allow it to operate in an unloaded or noncompressing condition.

A balance port 48 is provided in the wall of the cylinder 40 and communicates with the space outwardly of the piston heads 43 and 44 to permit balancing or equalizing of the pressure in the cylinder 40 outwardly of the two piston heads 43 and 44.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. The combination with a rotary compressor comprising a cylinder having suction and exhaust ports, a rotor therein, and a movable abutment between said suction and discharge ports, of means for controlling the loading and unloading of the compressor comprising a piston acted upon by suction pressure to permit loaded operation of the compressor and acted upon by receiver pressure to move said abutment into inoperative position for unloading the compressor, and pressure operated means controlling passage of fluid under receiver pressure to said piston.

2. In a compressor wherein is provided a cylinder, a rotor, a movable abutment and means normally urging the abutment toward the rotor, said abutment having a recess terminating in an engaging shoulder, and an abutment retracting head freely movable in the recess when moved in one direction but engageable with said shoulder when moved in the opposite direction for retracting the abutment and unloading the compressor.

3. In a compressor wherein is provided a cylinder, a rotor, a movable abutment and means normally urging the abutment toward the rotor, said abutment having a recess terminating in an engaging shoulder, and an abutment retracting head freely movable in the recess when moved in one direction but engageable with said shoulder when moved in the opposite direction for retracting the abutment and unloading the compressor, and pressure responsive means for controlling the movement of said head.

4. In a compressor wherein is provided a cylinder, a rotor, a movable abutment and means normally urging the abutment toward the rotor, said abutment comprising complementary wedge pieces having a recess terminating in an engaging shoulder and a passageway communicating with said recess, and an abutment retracting head freely movable in the recess when moved in one direction but engageable with said shoulder when moved in the opposite direction for retracting the abutment and unloading the compressor, said head having a stem projecting through said passageway, and a piston connected to said stem and movable in response to fluid pressure for controlling the position of said abutment.

5. In a rotary compressor comprising a cylinder, a rotor therein, and a movable abutment controlling the loading and unloading operation of the compressor, the combination of means for controlling the position of said abutment comprising a cylinder, a piston movable therein and connected to said abutment, means connecting said last named cylinder to the compressor suction to admit fluid under suction pressure at one side of the piston, and adjustable pressure operated means adapted to be set to open at a predetermined pressure to admit fluid under pressure to said cylinder at the other end of said piston.

6. The combination with a rotary compressor including a cylinder, a rotor and a movable abutment, of means'for loading and unloading the compressor comprising a cylinder, a piston mounted in the cylinder, means connecting said piston and abutment whereby movement of the piston in one direction will positively move the abutment into inoperative position and movement of the piston in a reverse direction will relieve the abutment for movement into operative position, said cylinder connected to the compressor suction to admit fluid under suction pressure at one end of the piston, and adjustable pressure operated means set to open at a predetermined pressure to admit fluid under pressure to said cylinder at the other end of said piston for moving the abutment into inoperative position.

7. The combination with a rotary compressor comprising a cylinder having suction and exhaust ports, a rotor therein, and a movable abutment between said suction and discharge ports, of means for controlling the loading and unloading of the compressor comprising a cylinder, at piston movable therein and connected to said abutment, said cylinder connected to the compressor suction to admit fluid under suction pressure at one end of said piston to permit loaded operation of the compressor, and adjustable pressure operated means set to operate at a predetermined pressure to admit fluid under pressure to said cylinder at the other end of said piston to move said abutment into inoperative posititon for unloading the compressor.

MICHAEL RIESNER. 

